Add turso cloud encryption example (#2199)

Author: avinassh

libsql/examples/encryption_remote.rs

@@ -0,0 +1,79 @@
+// Example: Connecting to an encrypted Turso Cloud database
+//
+// This example shows how to connect to a Turso Cloud database with
+// remote encryption using the rust driver.
+//
+// Documentation of encrypted databases - https://docs.turso.tech/cloud/encryption
+//
+// Usage:
+//
+//  export LIBSQL_DB_URL="libsql://your-db.aws-us-east-2.turso.io"
+//  export LIBSQL_AUTH_TOKEN="your-token"
+//  export LIBSQL_ENCRYPTION_KEY="encryption key in base 64 encoded format"
+//  cargo run --example encryption_remote
+//
+// The encryption key must be encoded in base64 format.
+
+use libsql::{params, Builder};
+use libsql::{EncryptionContext, EncryptionKey};
+
+#[tokio::main]
+async fn main() {
+    tracing_subscriber::fmt::init();
+
+    // The remote DB URL to use.
+    let db_url = std::env::var("LIBSQL_DB_URL").unwrap();
+
+    // The authentication token for the remote db
+    let auth_token = std::env::var("LIBSQL_AUTH_TOKEN").unwrap_or("".to_string());
+
+    // Optional encryption key for the database, if provided.
+    let encryption = if let Ok(key) = std::env::var("LIBSQL_ENCRYPTION_KEY") {
+        Some(EncryptionContext {
+            key: EncryptionKey::Base64Encoded(key),
+        })
+    } else {
+        None
+    };
+
+    let mut db_builder = Builder::new_remote(db_url, auth_token);
+    if let Some(enc) = encryption {
+        db_builder = db_builder.remote_encryption(enc);
+    }
+    let db = db_builder.build().await.unwrap();
+    let conn = db.connect().unwrap();
+
+    conn.execute(
+        r#"
+        CREATE TABLE IF NOT EXISTS guest_book_entries (
+            text TEXT
+        )"#,
+        (),
+    )
+    .await
+    .unwrap();
+
+    let mut input = String::new();
+    println!("Please write your entry to the guestbook:");
+    match std::io::stdin().read_line(&mut input) {
+        Ok(_) => {
+            println!("You entered: {}", input);
+            let params = params![input.as_str()];
+            conn.execute("INSERT INTO guest_book_entries (text) VALUES (?)", params)
+                .await
+                .unwrap();
+        }
+        Err(error) => {
+            eprintln!("Error reading input: {}", error);
+        }
+    }
+    let mut results = conn
+        .query("SELECT * FROM guest_book_entries", ())
+        .await
+        .unwrap();
+    println!("Guest book entries:");
+    while let Some(row) = results.next().await.unwrap() {
+        let text: String = row.get(0).unwrap();
+        println!("  {}", text);
+    }
+}